1. Field of the Invention
The present invention relates to a semiconductor structure and a manufacturing method thereof, and more particularly, to a semiconductor structure including a source/drain contact recessed by a recessing process for improving the process window and a manufacturing method thereof.
2. Description of the Prior Art
The development of semiconductor integrated circuit technology progresses continuously and circuit designs in products of the new generation become smaller and more complicated than those of the former generation. The amount and the density of the functional devices in each chip region are increased constantly according to the requirements of innovated products, and the size of each device has to become smaller accordingly. As shown in FIG. 1, in a traditional semiconductor structure 100, a plurality of gates 130 are disposed on a substrate 110, a gate protection layer 131 is formed on each of the gates 130, and a self-aligned contact structure 141 is formed between two adjacent gates 130. The self-aligned contact structure 141 is formed by filling an opening formed between the two adjacent gates 130 with a conductive material and performing a chemical mechanical polish (CMP) process, and the self-aligned contact structure 141 may be formed corresponding to a source/drain (not shown) between the gates 130. The self-aligned contact structure 141 is electrically isolated from the gates 130. After the CMP process mentioned above, top surfaces of the self-aligned contact structure 141, the gate protection layer 131, and a first gate contact 142 formed on another gate 130 are kept on the same level and leveled with one another. A second gate contact 160 is then formed to be connected to the first gate contact. The second gate contact 160 tends to contact the self-aligned contact structure 141 and a short circuit may occur between the self-aligned contact structure 141 and the gate 130 when there is an alignment shift in the process of forming the second gate contact 160 because the spacing between the gates 130 becomes smaller. Therefore, the process window is a problem to be improved.